The owner of the house we are living in is selling the house...what are our rights?

We currently live in a home managed by a property management company. The owner of the house wants to sell the house. When we were notified the management company told us we had an option to buy (which we are doing) and to not worry about the rent for the 1st of July. NOW that the buying process is in motion, the management company is trying to get rent for the 1st out of us. What are our rights as tenants if anyone knows!